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From:   Kalle Valo <kvalo@codeaurora.org>
To:     Alvin =?utf-8?Q?=C5=A0ipraga?= <alsi@bang-olufsen.dk>
Cc:     Wen Gong <wgong@codeaurora.org>,
        "Luis R . Rodriguez" <mcgrof@kernel.org>,
        linux-wireless@vger.kernel.org, ath10k@lists.infradead.org
Subject: Re: [PATCH] Revert "ath: add support for special 0x0 regulatory domain"
References: <20200730124923.271429-1-alsi@bang-olufsen.dk>
        <c21bfe94-2de8-8178-7762-5a9b068a0e4a@bang-olufsen.dk>
Date:   Thu, 27 Aug 2020 13:12:34 +0300
In-Reply-To: <c21bfe94-2de8-8178-7762-5a9b068a0e4a@bang-olufsen.dk> ("Alvin
        \=\?utf-8\?Q\?\=C5\=A0ipraga\=22's\?\= message of "Thu, 27 Aug 2020 09:59:20 +0200")
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Alvin =C5=A0ipraga <alsi@bang-olufsen.dk> writes:

> Hi Kalle,
>
> On 7/30/20 2:49 PM, Alvin =C5=A0ipraga wrote:
>> This reverts commit 2dc016599cfa9672a147528ca26d70c3654a5423.
>>
>> Per Atheros documentation to manufacturers, the EEPROM regulatory domain
>> code 0x0 must always map to "US". In particular, it should not map to a
>> custom world regulatory domain. For references, see [1] and [2] below.
>> Furthermore, __ath_regd_init() has a specific condition to set the
>> country code to "US" in this case, which emits the following log
>> message:
>>
>> [    7.814307] ath: EEPROM indicates default country code should be used
>>
>> The patch being reverted mistakenly maps 0x0 to the custom world
>> regulatory domain 0x64 - the most restrictive of the world regulatory
>> domains. The premise of the patch is that in the case of EEPROM
>> regulatory domain code 0x0, ath_is_world_regd() should return true. But,
>> as stated above, 0x0 should not map to a world regulatory domain, and so
>> the function should return false. The original behaviour, whereby
>> NL80211_REGDOM_SET_BY_COUNTRY_IE is ignored, was correct according to
>> the manufacturer's intent and should not have been changed.
>>
>> [1] https://wireless.wiki.kernel.org/en/users/drivers/ath#the_0x0_regula=
tory_domain
>> [2] http://article.gmane.org/gmane.linux.kernel.wireless.general/38410
>>
>> Fixes: 2dc016599cfa ("ath: add support for special 0x0 regulatory domain=
")
>> Cc: Wen Gong <wgong@codeaurora.org>
>> Cc: Luis R. Rodriguez <mcgrof@kernel.org>
>> Cc: linux-wireless@vger.kernel.org
>> Tested-on: QCA9880 hw2.0 PCI 10.2.4-1.0-00047
>> Signed-off-by: Alvin =C5=A0ipraga <alsi@bang-olufsen.dk>
>> ---
>>   drivers/net/wireless/ath/regd.c | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>
> Do you have any feedback on this patch? No problem if you simply have
> not looked yet - I am not sure what kind of lead time to expect on the
> list. But without the patch, a (correctly) programmed 0x0 (US) card
> will not be able to operate on 5GHz channels without some hacking. I
> have cited some references to justify reverting this patch, so I would
> like to know if anything further should be done to get this into
> future kernels?
>
> I wonder also if Wen Gong could comment, whose patch I am reverting in
> the first place. Maybe there is something I am missing?

I'm working on it, I just need to check something internally first.

BTW, Brian submitted an identical revert first so I'm planning to use
his patch instead of yours:

https://patchwork.kernel.org/patch/11573585/

--=20
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatc=
hes